It was developed by Microsoft within its .NET initiative and later approved as a standard by ECMA (ECMA-334) and ISO (ISO/IEC 23270:2006). C# is one of the programming languages designed for the Common Language Infrastructure (CLI).

Visual C# .NET is Microsoft's C# development tool. It includes an interactive development environment, visual designers for building Windows and Web applications, a compiler, and a debugger. Visual C# .NET is part of a suite of products, called Visual Studio .NET, that also includes Visual Basic .NET, Visual C++ .NET, and the JScript scripting language.

All of these languages provide access to the Microsoft .NET Framework, which includes a common execution engine and a rich class library. The .NET Framework defines a "Common Language Specification" (CLS), a sort of lingua franca that ensures seamless interoperability between CLS-compliant languages and class libraries.

History of C#

During the development of the .NET Framework, the class libraries were originally written using a managed code compiler system called Simple Managed C (SMC). In January 1999, Anders Hejlsberg formed a team to build a new language at the time called Cool, which stood for "C-like Object Oriented Language". Microsoft had considered keeping the name "Cool" as the final name of the language, but chose not to do so for trademark reasons. By the time the .NET project was publicly announced at the July 2000 Professional Developers Conference, the language had been renamed C#, and the class libraries and ASP.NET runtime had been ported to C#.

C#'s principal designer and lead architect at Microsoft is Anders Hejlsberg, who was previously involved with the design of Turbo Pascal, Embarcadero Delphi (formerly CodeGear Delphi, Inprise Delphi and Borland Delphi), and Visual J++. In interviews and technical papers he has stated that flaws in most major programming languages (e.g. C++, Java, Delphi, and Smalltalk) drove the fundamentals of the Common Language Runtime (CLR), which, in turn, drove the design of the C# language itself.

Since the release of C# 2.0 in November of 2005, the language has evolved increasingly. C# has added several major features to accommodate functional-style programming, culminating in their LINQ extensions released with C# 3.0 and its supporting framework of lambda expressions, extension methods, and anonymous classes. These features enable C# programmers to use functional programming techniques, such as closures, when it is advantageous to their application.

The LINQ extensions and the functional imports help developers reduce the amount of "boilerplate" code that is included in common tasks like querying a database, parsing an xml file, or searching through a data structure, shifting the emphasis onto the actual program logic to help improve readability and maintainability.

Imperative Programming: Imperative programming is focused on describing how a program operates. In computer science terminology, imperative programming is a programming paradigm that describes computation in terms of statements that change a program state. In much the same way that imperative mood in natural languages express commands to take action, imperative programs define sequences of commands for the computer to perform.

Object-Oriented Programming: Object-oriented programming attempts to provide a model for programming based on objects. Object-oriented programming integrates code and data using the concept of an "object". An object is an abstract data type with the addition of polymorphism and inheritance. An object has both state (data) and behavior (code).

Generic Programming: Generic programming is a style of computer programming in which algorithms are written in terms of types to-be-specified-later that are then instantiated when needed for specific types provided as parameters. This approach, pioneered by ML in 1973, permits writing common functions or types that differ only in the set of types on which they operate when used, thus reducing duplication.

Declarative Programming: declarative programming is a programming paradigm, a style of building the structure and elements of computer programs, that expresses the logic of a computation without describing its control flow.

Functional Programming: is a style of building the structure and elements of computer programs, that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It is a declarative programming paradigm, which means programming is done with expressions.

Component-Oriented Programming: Component-based software engineering (CBSE) (also known as component-based development (CBD)) is a branch of software engineering that emphasizes the separation of concerns in respect of the wide-ranging functionality available throughout a given software system.

C# is suitable for developing many applications due to its multi-programming feature, it is difficult to list all the applications written with C# because all the programming languages within the .NET framework can execute the code written with any of the .NET language. It is certain that C# is one of the programming languages that has a long life span.

Standardization and Licensing

In August 2000, Microsoft Corporation, Hewlett-Packard and Intel Corporation co-sponsored the submission of specifications for C# as well as the Common Language Infrastructure (CLI) to the standards organization Ecma International. In December 2001, ECMA released ECMA-334C# Language Specification. C# became an ISO standard in 2003 (ISO/IEC 23270:2003 - Information technology -- Programming languages -- C#). ECMA had previously adopted equivalent specifications as the 2nd edition of C#, in December 2002.

In June 2005, ECMA approved edition 3 of the C# specification, and updated ECMA-334. Additions included partial classes, anonymous methods, nullable types, and generics. In July 2005, ECMA submitted the standards and related TRs to ISO/IEC JTC 1 via the latter's Fast-Track process.

The C# language definition and the CLI are standardized under ISO and Ecma standards that provide reasonable and non-discriminatory licensing protection from patent claims. However, Microsoft uses C# and the CLI in its Base Class Library (BCL) that is the foundation of its proprietary .NET framework, and which provides a variety of non-standardized classes (extended I/O, GUI, Web services, etc.).

Some cases where Microsoft patents apply to standards used in the .NET framework are documented by Microsoft and the applicable patents are available on either RAND terms or through Microsoft's Open Specification Promise that releases patent rights to the public, but there is some concern and debate as to whether there are additional aspects patented by Microsoft that are not covered, which may deter independent implementations of the full framework.

Implementations

Microsoft is leading the development of a new open source C# compiler and set of tools, previously codenamed "Roslyn". The compiler, which is entirely written in managed code (C#), has been opened up and functionality surfaced as APIs. It is thus enabling developers to create refactoring and diagnostics tools.

Other C# compilers exist, often including an implementation of the Common Language Infrastructure and the .NET class libraries up to .NET 2.0:

The Mono project (open source C# compiler) - a complete open source implementation of the Common Language Infrastructure including the required framework libraries as they appear in the ECMA specification, and a nearly complete implementation of the Microsoft proprietary .NET class libraries up to .NET 3.5.

The DotGNU project (Open source C# compiler) - a nearly complete implementation of the Common Language Infrastructure including the required framework libraries as they appear in the ECMA specification, and subset of some of the remaining Microsoft proprietary .NET class libraries up to .NET 2.0.

Microsoft's Rotor project (currently called Shared Source Common Language Infrastructure) (licensed for educational and research use only) provides a shared source implementation of the CLR runtime and a C# compiler, and a subset of the required Common Language Infrastructure framework libraries in the ECMA specification (up to C# 2.0, and supported on Windows XP only).

Syntax

C# has the following syntax:

Semicolons are used to denote the end of a statement.

Curly brackets are used to group statements. Statements are commonly grouped into methods (functions), methods into classes, and classes into namespaces.

Variables are assigned using an equals sign, but compared using two consecutive equals signs.

Square brackets are used with arrays, both to declare them and to get a value at a given index in one of them.

Take a tour around the programming world today and see that the future is Sharp with C#